Robert Pires: Alexis Sanchez and Mesut Ozil are great but Arsenal are missing their most important player… Santi Cazorla

Losing Santi Cazorla to injury has been a key factor behind Arsenal's struggles this season, according to Robert Pires.

Arsene Wenger's side were expected to compete for the Premier League title this term but the north Londoners' challenge has failed to last the course.

The Gunners have slipped to sixth place in the table and are in real danger of missing out Champions League football next season.

Cazorla has not made a top-flight appearance since October and Pires is adamant the Spaniard's ongoing spell on the sidelines has robbed Wenger of one of his most influential players.

"When you see the names on the paper they are great players like Mesut Ozil and Alexis Sanchez.

"The most important [thing] is missing Santi Cazorla. He is one of the best players at Arsenal. He's been injured for four months now and this is a real problem for Arsenal," Pires told Sky Sports News.

Cazorla's initial injury was an Achilles problem but he is currently struggling to shake off a calf problem, having also endured ankle surgery in an attempt to cure the problem he suffered in a Champions League group stage game against Ludogortes Razgrad.

However, Wenger is hopeful the 32-year-old could return to action before the end of the season.

Saturday's clash with Manchester City will certainly come too soon for the Spaniard and Pires believes Wenger must convince his players that they still have plenty to fight for ahead of the run-in.

"The message from Wenger [must be] to say, 'the season is not finished - we are six points from the Champions League [places] and we need to fight'.

"I want to see a good reaction and a good spirit.

"When I see the guys on the pitch, the quality is very good but sometimes we need more commitment, more spirit, more fighting," insisted the Frenchman.